Mercurial > sdl-ios-xcode
view docs/man3/SDL_keysym.3 @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_keysym" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" .SH "NAME" SDL_keysym\- Keysym structure .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ Uint8 scancode; SDLKey sym; SDLMod mod; Uint16 unicode; } SDL_keysym;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBscancode\fR Hardware specific scancode .TP 20 \fBsym\fR SDL virtual keysym .TP 20 \fBmod\fR Current key modifiers .TP 20 \fBunicode\fR Translated character .SH "DESCRIPTION" .PP The \fBSDL_keysym\fR structure is used by reporting key presses and releases since it is a part of the \fI\fBSDL_KeyboardEvent\fR\fR\&. .PP The \fBscancode\fR field should generally be left alone, it is the hardware dependent scancode returned by the keyboard\&. The \fBsym\fR field is extremely useful\&. It is the SDL-defined value of the key (see \fISDL Key Syms\fR\&. This field is very useful when you are checking for certain key presses, like so: .PP .nf \f(CW\&. \&. while(SDL_PollEvent(&event)){ switch(event\&.type){ case SDL_KEYDOWN: if(event\&.key\&.keysym\&.sym==SDLK_LEFT) move_left(); break; \&. \&. \&. } } \&. \&.\fR .fi .PP \fBmod\fR stores the current state of the keyboard modifiers as explained in \fI\fBSDL_GetModState\fP\fR\&. The \fBunicode\fR is only used when UNICODE translation is enabled with \fI\fBSDL_EnableUNICODE\fP\fR\&. If \fBunicode\fR is non-zero then this a the UNICODE character corresponding to the keypress\&. If the high 9 bits of the character are 0, then this maps to the equivalent ASCII character: .PP .nf \f(CWchar ch; if ( (keysym\&.unicode & 0xFF80) == 0 ) { ch = keysym\&.unicode & 0x7F; } else { printf("An International Character\&. "); }\fR .fi .PP UNICODE translation does have a slight overhead so don\&'t enable it unless its needed\&. .SH "SEE ALSO" .PP \fI\fBSDLKey\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00